1. Field of the Invention
The present invention relates to a method for concentrating oxygen isotopes, and more particularly, to a method for selectively concentrating the stable oxygen isotopes, 17O and/or 18O, which exist in extremely small natural abundance, by using an ozone photodissociation reaction or a peroxide photodissociation reaction.
2. Description of the Related Art
Since 17O and 18O, which are oxygen isotopes used as tracers in the fields of chemistry and medicine, exist in extremely small natural abundance, it is necessary that they be concentrated. A known method for concentrating 18O consists of obtaining a product that contains 18O by selectively photodissociating a saturated chain ether that contains 18O by irradiating it with laser light (refer to, for example, Japanese Examined Patent Application, Second Publication No. 6-102134). Other methods include a method for selectively concentrating 18O by irradiating formaldehyde or carbon monoxide with laser light.
However, for reasons such as a low concentration rate, low utilization efficiency of the light that contributes to the reaction, low luminescence efficiency of the laser light and the necessity for post-processing for extracting the concentrated chemical species, the methods of the prior art have not been established industrially. Although the concentration of oxygen isotopes using a distillation procedure has also been proposed, problems are encountered in order to increase the degree of concentration, such as increased size of the device and the start-up time of the device being extremely long.
Therefore, the object of the present invention is to provide a method for concentrating oxygen isotopes that are capable of concentrating a oxygen isotope either in the state of the stable oxygen isotopes of 17O or 18O, or in a substance such as water having a simple molecular structure.